Heat a large pot or dutch oven over your stove at high heat. Add a mist of olive oil spray and let it get nice and hot.
Chop your flank steak into bite size pieces, sprinkle liberally on both sides with kosher salt, and a little pepper. Sear in batches, one layer deep, until it’s all done. Let it sit for a bit to get some color without moving. You'll want to cook for just a minute or two before flipping, then about one minute on the other side. Remove from pan and set aside.
Add a mist of oil spray to your pot and add your diced onions and a pinch of salt. Let them cook for a few minutes until fragrant and tender. Then add celery, carrots, thyme, salt, and pepper. Let them cook for 5-7 minutes until the veggies are tender.
Add tomato paste and garlic and cook for one more minute. Add wine and let it sizzle and cook for another minute, scraping all the browned bits off the bottom of the pot. Add beef broth and turn down to medium. Chop your cooked steak smaller if you like, and add it back into the soup.
While the soup simmers, steam your cauliflower using your preferred method. I just like to buy fresh bags of florets where I can snip the corner and microwave right in the bag because it's EASY and because it creates zero dishes. In a large blender, blend your steamed cauliflower and diced tomatoes until smooth.
Pour blended cauliflower mixture into the soup and combine well to thicken it up. Add frozen peas and let it simmer until you're ready to eat!